Lymphoid cells have unique properties in cell growth ability in comparison with many other somatic cells. Namely, lymphoid cells, similar to many other somatic cells, are differentiated from a hematopoietic stem cell to mature cells via many steps of cell division, and enter interphase (G0/G1). After that, if they are stimulated with an antigen or a special growth factor, they again enter to a cell cycle and increase a clone with a redifferentiation, and then return to interphase (memory cells). In addition to functional differentiation and expression specific to lymphoid cells, such repeated cell proliferation (clone proliferation) is one of the big factors in an immune response of an organism.